When members add a post to a group page or to their feed, I want them to be able to easily choose a topic from the list of topics I have already created. 

However, when they click "Add Topics" they see a blank field - meaning that they need to know which topics they want to add their post to before they even start writing. This is not optimal because the purpose of the site is to share and find information easily on their illness. 

They need see a drop down list of all the topics available when the "add topics" link is clicked. Then they can choose as many topics as they like.

Is this possible to set up already ?